Here is a copy from discord with steps to sync again (it helped me):

Hello @everyone, (Reminder)
To get back onto the right chain; you will need to download a patched version of the wallet (available here https://github.com/deftchain/deft/releases/download/0.15.1/deft-qt.zip).
@gj has also compiled the patched version for Apple https://minkiz.co/noodlings/dft/Deft-Qt.dmg
Once you have it, create a shortcut to the file and add -reindex to the launch target (as shown).
Then - launch the wallet using the shortcut, and leave it run.
Its a good idea to remove -reindex from the shortcut immediately afterwards; as this is a fairly slow process and having to go through it more than once (by forgetting and leaving it there) would be fairly painful.
James xx